CM's servers: Spam Rating / MX Server


first off thanks for an amazing tool, good job guys/gals!

Since I just started with CM I have not much experience with it yet, especially concerning the server side of things:
My client's server admin mentioned that sending the mails via an external server and from my clients e-mail address would instantly put it on a spam rating of 5.0 (at 6.0 the mail won't be delivered anymore) because the servers IP (namely CM's) would not match up with the MX entry for that e-mail domain (

I do realize that that's why you at CM included the authenticated server options (DomainKeys/Sender ID) which makes sense for private addresses at the big providers that support them but probably not so much for B2B contacts who have their own mailservers (unless they support them).

So my client's server admin (not knowing CM of course) suggested putting the sender's server as a secondary MX server entry on a new SUBdomain (

Does that make any sense? My thoughts about that: 1. CM naturally sends from various IP-addresses, could you enter several? 2. Isn't that somehow spoofing and thus malpractice?

I would appreciate any insights on this matter, as soon as I get more experience with CM, I'll be happy to help as well.

Thanks in advance,

Dave Dave, 7 years ago

Hey Benedikt,

Thanks for getting in touch about this. It's great to see your clients server admin being so proactive about this, but rest assured this won't pose any deliverability problems for you. Here's why.

While you can set your own "from address" and "reply-to address" for each campaign you send, the return-path of the email will still point back to our servers. This is the address receiving mail servers use to ensure correct reverse DNS is set up, some forms of authentication and host of other checks. Because of this, any emails you send from your own domain name still won't cause any issues delivering your campaigns.

To make this nice and clear to your clients server admin though, I'd recommend sending them a simple test campaign (to less than 5 recipients is free) so they can check this out for themselves.

vince, 7 years ago

Don't clients have to add your server domain into their DNS SPF record

bene.b, 7 years ago

Hi Dave,

thanks for getting back to me. I will test it especially with the server admin, good idea, I don't want him to claim that the whole campaign is going to be marked as spam...

I wasn't clear enough about something before and thus it was a bit of a misunderstanding I think: Of course the usual mail correspondence remains unaffected by me sending out campaigns (via CM). But the server admin's point was: When he would receive the campaign it would instantly get a spam ranking of 5.0 of 6.0 because the IP address of CM's servers isn't set up as an MX server for my client's domain.
Which is a weird setting considering that outgoing e-mails via an e-mail client are going out through the ISP's SMTP and not necessarily through the e-mail provider's.

I hope this makes sense. I'm just looking into all this, including SPF, thanks vince.
Thanks for any more input on this.

bene.b, 7 years ago

Does anybody have more insights on this matter maybe?
Thanks, I'd appreciate it!

Dave Dave, 7 years ago

Hey Bne,

Thanks for the follow up, but as I mentioned, definitely run that test with your admin guy. I'm confident you won't have a spam issue, as it's the return-path address they will use when validating the email, not your from address. because of that you shouldn't see any issues. Would love to hear from you after running the test to make sure that was the case.

bene.b, 7 years ago

Thanks Dave, I will post a follow up here!

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